US 3186256 A
Description (OCR text may contain errors)
L. REZNICK June 1, 1965 SAFETY GUARDS FOR BRAKES, PUNCH PRESSES AND SIMILAR MACHINES Original Filed Dec. 27, 1961 I FIGS INVENTOR, LOUIS REZNICK/ AT TORN EY United States Patent 3,186,256 SAFETY GUARDS FUR BRAKES, PUNCH PRESE AND STMILAR MACHINES Louis Reznick, 231 Brightwater Court, Brooklyn, N.Y. Continuation of application Ser. N 162,528, Dec. 27, 1961. This application .luiy 22, 1963, Ser. No. 297,733 Claims. ((11. 74-415) This application is a continuation of my application Serial No. 162,528 filed December 27, 1961, which is now abandoned.
The present invention relates to safety guards for power-driven machinery and more particularly to a type adaptable for use on power brakes, punch presses and the like.
A power brake is a machine for bending metal sheets and essentially includes a ram carrying a male die part, movable therewith towards and then away from the female die part mounted on a fixed bed. The female die part is an upright channel. In operating the machine to make .a bend, the sheet portion in front of the die is swung upward with extreme rapidity. In the trade, this occurrence is called whip. The safety guard must of course be in front of the die and offer clearance for feeding a sheet between the die parts, and yet guard against the entrance of a finger.
An object of this invention is to provide a novel and improved safety guard for a power brake, which will be automatically shifted in proper time to allow the upward movement of the whipped forward portion of the work so that such movement is unmolested, whether ram movernent is speedy or slow. At all times, of course, the guard shall be in such position that there is no possibility of hurt to the operator.
Another object thereof is to provide automatic safety guards for power brakes, punch presses and the like, which are reasonably cheap to manufacture, easy to install and efficient in carrying out the purposes for which they are designed.
For the practice of this invention, one form it may assume is to have the safety guard be a vertically positioned panel of two elongated, horizontally extending, hingedtogether sections which are one above the other and close in front of the die parts. The extent of the panel is beyond the ends of the dies and when the ram is up, said guard covers access to the space between the die parts, except for admission of a sheet metal piece to be worked on. Hence, the normal position of the guard is to have its lower edge a proper but safe distance from the upper plane of the female die part on the mach-ines bed. The
height of the lower section on the machine, is much less than that of the upper section of the guard, for the swinging of the lower section is to provide only the clearance necessary to remove the work when the operation is completcd. It is essential that the lower guard section shall be able to swing in front of the plane of the upper section, but not to a position in back of such plane to give an opening incompatible with the guards purpose. The guard is preferably light weight and it is most practical to have it of transparent plastic plate stock, for it is suspended fast to the upwardly-urged armatures of solenoids fixed on the frame of the machine; the scope of such upward movement when the solenoid coils are actuated, being sulficient to raise the guard to clear the work to allow unhindered upswing of the work portion which is in front of the dies. The circuit of the solenoids is controlled by a switch mounted on the machine frame and such switch is oper ated automatically .by the downward movement of the ram to actuate the solenoids to raise the guard immediately at or very slightly before the upper die touches the work. Of course, on the rams upward movement, said switch will return to the condition to open the solenoid circuit, whereupon the guard will fall to its normal lowered position. Said switch should be shielded or positioned that it be held from accidental operation.
For another embodiment, a cylinder apparatus may be used in place of the solenoid, in which instance the upper section of the safety guard is attached to the piston rod and said cylinder controlled by an electrically-operated valve; the mentioned circuit, controlling said valve.
Although I have shown a power brake in the illustrated embodiment, the association and operation of the safety apparatus herein taught, when incorporated on a power punch press or similar machine having a reciprocatable ram acting downwardly towards and upwardly from a fixed bed, are identical as herein set forth applied to the brake.
In the accompanying drawing forming part of this specification, similar characters of reference indicate corresponding parts in all the views.
FIG. 1 is a fragmentary front view of a power brake equipped with a safety guard embodying the teachings of this invention. Here, the machine is in normal rest condition. The ram is up. The safety guard is lowered with its sections co-planar. Movement thereof is effected by means of solenoids.
FIG. 2 is .a section drawn to an enlarged scale, taken at line 2-2 in FIG. 1 and shows .a metal sheet in position to be worked on.
FIG. 3 is a similar section taken at line 2-2 in FIG. 1, but here the machine is shown in condition where the bend in the work has just been completed by bringing the ram down. The safety guard has been automatically shifted .to permit the whip unmolested.
FIG. 4 is .a fragmentary front view where in plaee of each solenoid previously employed, there now is a cylinder means controlled by an electrically-openated Valve, to e fect lifting of the safety guard.
FIG. 5 is a diagrammatic showing of the electrical circuit which may be employed to operate the machine and its safety guard.
In the drawing, the numeral designates generally a power brake, but it may be a power punch press or similar machine, on whose frame 16, the ram 17 is slidably mounted for movement towards and then away from the machines bed 18. The ram carries the male die part 19 which cooperates with the female die part 20 on the bed, to make a bend 21 across a metal sheet 22, which may initially be laid on a table 23 with its forward edge against a properly positioned stop 24, to determine the position of the line of bend on the work. The balance of the machine structure is not shown because it is well known and forms no part of this invention. However, I have indicated the electrical circuit of the machines motor 25, because in the embodiment described, the solenoids 26 are actuated by the main power lines 27, though they may have. their own independent power supply as for instance from a storage battery not shown.
The safety guard indicated generally by the numeral 28, comprises two panel sections 29, 30 in a vertical plane, close to and in front of the dies 19, 20. Each such section is a horizontally positioned elongated member of plate stock, preferably of a transparent plastic sold under the trademark Lucite or Plexiglas. These sections are one atop the other and hinged at 31, so that the lower section 29 'can be swung only forwardly upwardly to allow removal of the finished work when the ram 17 returns to its normal raised position whereupon the guard 28 is again in its lowermost position. The upper section 30 is suspended fast by means of bolts 44 to plates 45 at the lower ends of the respective armatures 32 of the solenoids 26, which from a normal lowered position, are raised upon actuation of the solenoid coils, and they fall to such lowered position upon deactuation of said coils;
3 said coils being fixed to the machine frame and the scope of movement of said armatures being proper for the required safety guard movement.
In the set-up shown in FIG. 2, when the ram 17 is lowered to make the bend 21 as shown in FIG. 3, the forward part of the work 22 will swing upward. Such upward swing commences immediately after the upper die 19 contacts the fiat sheet. Hence, I have a normally open switch 33 fixed on the frame of the machine at a position that its spring biased operating member 33' is moved to close the switch by a cam piece 34 fixed on the ram, when the ram has reached such position that the die 19 just has come into contact with the sheet 22, or even a bit before such contact occurs, thereby actuating the solenoids 26 and the guard 28 is quickly lifted as shown in FIG. 3 at the start of bending the work. Said cam holds the switch closed until the ram has moved upward on its return stroke where the operating member 33' is free and so the switch 33 is thereupon opened, causing the deactuation of the solenoids 26 and hence the guard 28 falls to its normal low position as shown in FIG. 2. When the ram is raised it stops. For example, the machine is equipped with a pedal-operated one-revolution clutch suitably interposed to eifect one cycle of ram movement for each manual operation of the clutch. This arrangement is not shown, because it is well known and is no part of this invention.
One electrical circuit arrangement applicable herein is shown in FIG. 4, where the machines motor and the solenoids 26 receive their power from the lines 27. A switch 35 is interposed in one of said lines to connect and disconnect the power, and the switch 33 is interposed to control the application of power to said solenoids. For a more particular description of the circuit illustrated, it is noted that one terminal of the switch 35 is connected to one of the power lines; the other terminal of such switch being connected to one of the terminals of the solenoids and the motor. The other terminals of the solenoids are connected to one of the terminals of the switch 33; the other power line being connected to the motor and the other terminal of the switch 33.
To set the machine for operation, the switch 35 is closed to run the motor. At every operation of the press as determined by the working of the one-revolution clutch mentioned; the switch 33 will be operated as determined by the position of the ram, to cause the movement of the guard 28, in the manner herebefore set forth.
In place of each solenoid 26, I may substitute a suitable cylinder apparatus 36, whose piston rod 37 is attached to the safety guards upper section and whose I electrically-operated control valve 38 is likewise mounted on the supporting bar or beam 39. The solenoid 40, operating the valve 38, now takes the place of a solenoid 26 in the circuit shown in FIG. 5, and operation of the machine is otherwise the same as set forth previously herein. Said cylinder apparatus is preferably operated by compressed air, but may be of the steam or hydraulic types. The term cylinder apparatus herein shall be deemed to include all such media for cylinder operation.
It is advisable to be able to adjust the initial position of the guard. For this purpose the bar 39 may have its position adjusted up or down along the vertical leg of an angle piece as 41 at each end of the machines frame, and frontward and rearward, by adjusting the position of the angle pieces 41 along the horizontal leg of the fixed angle pieces as 42. The switch 33 may be at the rear of the machine on a bar 43.
This invention is capable of numerous forms and various applications without departing from the essential features herein disclosed. .It is therefore intended and desired that the embodiments shown herein shall be deemed illustrative and not restrictive and that the patent shall cover all patentable novelty herein set forth; reference being had to the following claims rather than to the specific description herein to indicate the scope of this invention.
1. In combination with a machine having a die part fixed on a ram which is movable on the machines frame, downwardly towards and upwardly from a co-operating die part fixed on a fixed bed, a normally upright panel structure safety guard positioned in front of said die parts and extending sufiiciently downward to permit the admission of a metal sheet under said safety guard and thence between said die parts, but to exclude the admission of an operators finger to the die parts when the sheet is out of the machine; said safety guard comprising two sections, one above the other and in hinged relation so that the lower section can be swung only upwardly and forwardly from its normal position and then downwardly rearwardly back to such normal position, a first means including an electrically operated device, and a member movably mounted in relation to the frame, which member is moved in one direction when said device is actuated and in the opposite direction when said device is deactuated, a second means connecting the said member with the upper section of the safety guard, whereby on actuation of said device, the safety guard will be raised and upon deactuation of said device, the safety guard will return to its normal lowered position, an electrical circuit to actuate said device, a switch interposed in said circuit to control the actuation of said device; said switch being fixed on the frame and normally in open condition and an element carried on the ram, adapted to close said switch when the ram is at a predetermined lowered position.
2. An apparatus as defined in claim 1, wherein the switch has a spring-biased operating member; the element on the ram being a cam which is adapted to shift said operating member to bring the switch into closed condition.
3. An apparatus as defined in claim 1, wherein said element is so positioned on the ram and said switch is so positioned on the frame that the lowered position of the ram whereat the switch will be closed, is when the distance between the bottom plane of the upper die and the top plane of the lower die, is about the thickness of the metal to be worked.
4. An apparatus as defined in claim 1, wherein the first means is a solenoid and the armature thereof is the mentioned member; the coil of said solenoid, being the electrically-operated device.
5. An apparatus as defined in claim 1, wherein the first means is a cylinder apparatus and the piston rod thereof is the mentioned member; said cylinder being controlled by an electrically operated valve which is the electricallyoperated device.
References Cited by the Examiner UNITED STATES PATENTS 2,724,287 11/55 Knoth 74-615 X FOREIGN PATENTS 781,722 8/57 Great Britain.
BROUGHTON G. DURHAM, Primary Examiner. MILTON KAUFMAN. Examiner.